This invention relates to lasers and more particularly to an electronically switchable multiwavelength laser system.
Many lasing materials exhibit the capability of producing laser section at several different wavelengths. As an example, a Nd:YAG (neodymium yttrium aluminum garnet) laser can be caused to lase at many different wavelengths from approximately 970 nanometers to 1800 nanometers, two of the strongest lines in that range being at 1064 nanometers and 1318.8 nanometers (commonly referred to as 1.06.mu. and 1.32.mu., respectively). To change from one wavelength to another it has been necessary in the past to mechanically change or replace all or part of the optical components within the laser resonator. This technique is tedius and time consuming and necessitates inactivation of the laser during this period.
The need to switch between optical wavelengths rapidly is exemplified in the field of optical ranging through the atmosphere by means of an optical radar system. Operation of such a ranging system at a single wavelength can result in atmospheric refraction errors of several feet for a range of 20-100 Km. Utilization of two wavelengths simultaneously or immediately following one another enables a measure of refractive effects of the atmosphere on the beam to produce considerably more accurate range information. More specifically, the refractive effects at one wavelength are different from those effects at another wavelength and this measurable difference enables compensation of the refractive effects of the atmosphere. There is no known laser system which is capable of rapidly switching between two or more different wavelengths so as to have utility for this purpose.
This invention is directed to a system and method which overcomes the above problems.